1. Field of Art
Embodiments relate to forming a thin film using radicals generated by plasma.
2. Description of Art
Thin film deposition by means of plasma-enhanced chemical vapor deposition (PECVD) or plasma-enhanced atomic layer deposition (PEALD) results in lower deposition temperature due to plasma energy. However, the substrate may be damaged due to direct exposed to the plasma.
Remote plasma may be employed to avoid the issue of damaging the substrate. However, the extended distance between the substrate and plasma may give rise to the following issues: (i) reaction with a source precursor becomes insufficient for radicals having short lifespan, and (ii) the thickness and composition of the thin film become inconsistent because of poor plasma uniformity.
The source precursor may be decomposed when exposed to the plasma or radicals generated by the plasma. Therefore, when attempting PEALD, plasma of a reactant precursor (e.g., O2, H2, NH3, N2, and radicals thereof) has to be injected after the source precursor becomes adsorbed on the substrate.
A conventional process of PEALD may include the sequential steps in the following order: (i) adsorption of source precursor, (ii) purging, (iii) injection of reactant precursor plasma, and (iv) purging. In order to improve deposition rate, the process may be modified so that the steps are performed in the following order: (i) adsorption of source precursor, (ii) injection of reactant precursor plasma, and (iii) purging. However, since the adsorption of the source precursor determines the deposition rate of PEALD, improvement of the deposition rate is very limited.